Energy absorbing knee bolster assembly

ABSTRACT

An energy absorbing knee bolster assembly for a vehicle includes a knee deflector for partially surrounding a steering column of the vehicle. The energy absorbing knee bolster assembly also includes left and right energy absorbing knee bolster brackets on opposite sides of the knee deflector. The knee deflector and the energy absorbing knee bolster brackets are integral, unitary, and one-piece.

TECHNICAL FIELD

[0001] The present invention relates generally to knee bolsters forvehicles and, more particularly, to an energy absorbing knee bolsterassembly for a vehicle.

BACKGROUND OF THE INVENTION

[0002] It is known to provide a vehicle interior with a knee bolsterassembly that straddles a steering column at a location below a steeringwheel and generally on a lower portion of an instrument panel for avehicle such as an automotive vehicle. Typically, the knee bolster isdesigned to absorb the impact of an occupant's knees during a forwardcollision as a means of supplementing seat belts and other occupantrestraints.

[0003] An example of such a knee bolster assembly is disclosed in U.S.Pat. No. 6,145,880 to White et al. In this patent, the knee bolsterassembly includes a central bracket adapted for partially surroundingthe steering column and a foam element mounted on the central bracket.The knee bolster assembly also includes left and right knee bracketsmounted on opposite sides of the central bracket. The knee brackets eachhave a generally D-shaped cross-section including a convex rear wallpositionable adjacent a vehicle driver occupant such that upon loadingby the vehicle driver occupant, the knee brackets deform about multiple,nonspecific bend lines for absorption of energy. The knee bracketspreferably include inner and forward walls rigidly secured to thecentral bracket and outer and rear walls that significantly deform forabsorption of energy. The central bracket and knee brackets are separateparts formed as three progression steel stampings.

[0004] Although the above knee bolster assembly has worked, it isdesirable to provide a new knee bolster assembly for a vehicle. It isalso desirable to provide a knee bolster assembly having a thermoplasticknee deflector and energy absorbing knee bolster brackets. It is furtherdesirable to provide a knee bolster assembly that has a thermoplasticknee deflector and energy absorbing brackets that use a one-piecedesign. Therefore, there is a need in the art to provide an energyabsorbing knee bolster assembly for a vehicle that meets these desires.

SUMMARY OF THE INVENTION

[0005] It is, therefore, one object of the present invention to providea new energy absorbing knee bolster assembly for a vehicle.

[0006] It is another object of the present invention to provide anenergy absorbing knee bolster assembly for a vehicle that has athermoplastic knee deflector and energy absorbing knee bolster brackets.

[0007] It is yet another object of the present invention to provide anenergy absorbing knee bolster assembly that has a one-piece design.

[0008] To achieve the foregoing objects, the present invention is anenergy absorbing knee bolster assembly for a vehicle. The energyabsorbing knee bolster assembly includes a knee deflector for partiallysurrounding a steering column of the vehicle. The energy absorbing kneebolster assembly also includes left and right energy absorbing kneebolster brackets on opposite sides of the knee deflector. The kneedeflector and energy absorbing knee bolster brackets are integral,unitary, and one-piece.

[0009] The energy absorbing knee bolster assembly has a one-piece designthat replaces three steel stampings in the current manufacturingprocess. The energy absorbing knee bolster assembly also allows fortuning the stiffness of the knee deflector by including gas assistedtubes to stiffen the knee deflector. The energy absorbingcharacteristics of the knee deflector may be tuned by altering orvarying the wall thickness of these tubes by the amount and pressure ofthe gas injected during the molding process without requiring a toolingchange. The energy absorbing knee bolster assembly may have severaldifferent stiffness parts that can be produced in the same tool to allowthe parts to be evaluated to obtain the best femur loads for a givenvehicle pulse. Further, the energy absorbing knee bolster assemblyeliminates three progression steel stampings with one injection moldingtool and provides a tunable part for energy absorption, without toolingchanges. The energy absorbing knee bolster assembly requires only theprocess of gas assisting and foam durometer to adjust the stiffness ofthe assembly. The knee bolster brackets are filled with frangible foamto increase the crush force required and to allow the brackets to betuned to the vehicle crash pulse by varying the durometer of the foam,allowing the stiffness to be altered without changing the tool.

[0010] Other objects and features of the present invention will bereadily appreciated, as the same becomes better understood, afterreading the subsequent description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a right perspective view of an energy absorbing kneebolster assembly, according to the present invention, illustrated inoperational relationship with a vehicle.

[0012]FIG. 2 is a left perspective view of the energy absorbing kneebolster assembly of FIG. 1 with a portion of the vehicle removed.

[0013]FIG. 3 is a perspective view of the energy absorbing knee bolsterassembly of FIG. 1 with the vehicle removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] Referring to the drawings, one embodiment of an energy absorbingknee bolster assembly 10, according to the present invention, is shownfor a vehicle such as an automotive vehicle, generally indicated at 12.The vehicle 12 includes an instrument panel 14 positioned in front ofvehicle occupants (not shown) in an occupant compartment thereof. Thevehicle 12 also includes a steering column 16 extending below theinstrument panel 14 and into the occupant compartment to support asteering wheel (not shown). A vehicle driver occupant's knees aretypically straddled on either side of the steering column 16. Thesteering column 16 is attached to a rigid steering column bracket (notshown). The instrument panel 14 may include other underlying rigidvehicle structure onto which the energy absorbing knee bolster assembly10 may be mounted for supplemental protection of the lower extremitiesof the vehicle driver occupant. In FIG. 1, the location of the energyabsorbing knee bolster assembly 10 is for a vehicle driver's sideapplication. It should be appreciated that, except for the energyabsorbing knee bolster assembly 10, the vehicle 12 is conventional andknown in the art.

[0015] Referring to FIGS. 1 through 3, the energy absorbing knee bolsterassembly 10 includes a thermoplastic knee deflector 18. The kneedeflector 18 extends laterally and vertically. The knee deflector 18 ispreferably generally C-shaped having flanges 19 at the ends thereofextending laterally. The flanges 19 are attached to the instrument panel14 by suitable means such as fasteners (not shown). The knee deflector18 includes at least one, preferably, a plurality of tubes 20 extendinglaterally and spaced vertically. The tubes 20 are gas assisted or filledwith gas to provide a means of tuning the stiffness of the kneedeflector 18 and to stiffen the knee deflector 18. The wall thickness ofthe tubes 20 can be varied by the amount and pressure of the gasinjected during a molding process. The knee deflector 18, flanges 19,and tubes 20 are integral, unitary, and formed as one-piece from athermoplastic material such as polypropylene. It should be appreciatedthat the knee deflector 18, flanges 19 and tubes 20 are molded from thethermoplastic material by conventional gas-assisted injection moldingwhich is conventional and known in the art.

[0016] The energy absorbing knee bolster assembly 10 also includes rightand left energy absorbing knee bolster brackets 22 and 24 extending fromthe knee deflector 18. The brackets 22 and 24 are spaced laterally andlocated at the lateral ends of the knee deflector 18. The brackets 22and 24 extend longitudinally from the flanges 19 of the knee deflector18. Each of the brackets 22 and 24 have a plurality of sections 26 beinggenerally hollow and rectangular in cross-sectional shape. The sections26 extend generally vertically. The sections 26 have a collapseinitiator on either one or both longitudinal ends. The collapseinitiator is either a recess 28 or a projection 30 at each lateral edgeextending longitudinally and vertically to form a stepped configuration.The projections 30 are received in the recesses 28 and the recesses 28and projections 30 cooperate with each other. It should be appreciatedthat the recesses 28 and projections 30 of the brackets 22 and 24 are ofa molded design to allows the sections 26 to fracture and collapse oneach other to insure that the energy absorbed is not returned to theoccupant of the vehicle during a vehicle impact.

[0017] The brackets 22 and 24, knee deflector 18, and tubes 20 areintegral, unitary, and formed as one-piece from a thermoplastic materialsuch as polypropylene. It should be appreciated that the brackets 22 and24, knee deflector 18, and tubes 20 are molded from the thermoplasticmaterial by conventional gas-assisted injection molding which isconventional and known in the art.

[0018] The energy absorbing knee bolster assembly 10 further includes afrangible foam 32 disposed inside the sections 26 of the brackets 22 and24. The foam 32 is made of a plastic material such as polystyrene. Thefoam 32 has a durometer of approximately 60 D. The foam 32 increases thecrush force required for the brackets 22 and 24 and to allow thebrackets 22 and 24 to be tuned to the vehicle crash pulse by varying thedurometer of the foam 32. It should be appreciated that the foam 32allows the stiffness of the brackets 22 and 24 to be altered. It shouldalso be appreciated that the knee deflector 18 and brackets 22 and 24are made of a one-piece design that replaces three steel stampings.

[0019] In operation of the energy absorbing knee bolster assembly 10,during impact, the knee deflector 18 will deform and deflect laterally.The tubes 20 provide a tuned stiffness to the knee deflector 18 toprovide a predetermined amount of deflection. The sections 26 of thebrackets 22 and 24 fracture and collapse on each other to insure thatthe energy absorbed is not returned to the occupant of the vehicleduring a vehicle impact.

[0020] The present invention has been described in an illustrativemanner. It is to be understood that the terminology, which has beenused, is intended to be in the nature of words of description ratherthan of limitation.

[0021] Many modifications and variations of the present invention arepossible in light of the above teachings. Therefore, within the scope ofthe appended claims, the present invention may be practiced other thanas specifically described.

1. An energy absorbing knee bolster assembly for a vehicle comprising: aknee deflector for partially surrounding a steering column of thevehicle; and left and right energy absorbing knee bolster brackets onopposite sides of said knee deflector, wherein said knee deflector andsaid energy absorbing knee bolster brackets are integral, unitary, andone-piece.
 2. An energy absorbing knee bolster assembly as set forth inclaim 1 wherein said knee deflector includes at least one tube extendinglaterally therealong.
 3. An energy absorbing knee bolster assembly asset forth in claim 2 wherein said at least one tube is filled with agas.
 4. An energy absorbing knee bolster assembly as set forth in claim1 including a foam disposed within said energy absorbing knee bolsterbrackets.
 5. An energy absorbing knee bolster assembly as set forth inclaim 4 wherein said foam is a frangible foam.
 6. An energy absorbingknee bolster assembly as set forth in claim 1 wherein said kneedeflector is made of a thermoplastic material.
 7. An energy absorbingknee bolster assembly as set forth in claim 1 wherein said energyabsorbing knee bolster brackets are made of a thermoplastic material. 8.An energy absorbing knee bolster assembly as set forth in claim 1wherein each of said energy absorbing knee bolster brackets comprise aplurality of sections.
 9. An energy absorbing knee bolster assembly asset forth in claim 8 wherein said sections have at least one collapseinitiator therein.
 10. An energy absorbing knee bolster assembly as setforth in claim 9 wherein said at least one collapse initiator comprisesa projection and a recess on adjacent said sections, said projectionbeing received in said recess.
 11. An energy absorbing knee bolsterassembly for a vehicle comprising: a knee deflector for partiallysurrounding a steering column of the vehicle, said knee deflectorincluding a plurality of tubes extending therealong; and left and rightenergy absorbing knee bolster brackets on opposite sides of said kneedeflector, wherein said knee deflector and said energy absorbing kneebolster brackets are integral, unitary, and one-piece.
 12. An energyabsorbing knee bolster assembly as set forth in claim 11 wherein saidtubes are filled with a gas.
 13. An energy absorbing knee bolsterassembly as set forth in claim 11 including a foam disposed within saidenergy absorbing knee bolster brackets.
 14. An energy absorbing kneebolster assembly as set forth in claim 13 wherein said foam is afrangible foam.
 15. An energy absorbing knee bolster assembly as setforth in claim 11 wherein said knee deflector is made of a thermoplasticmaterial.
 16. An energy absorbing knee bolster assembly as set forth inclaim 11 wherein said energy absorbing knee bolster brackets are made ofa thermoplastic material.
 17. An energy absorbing knee bolster assemblyas set forth in claim 11 wherein each of said energy absorbing kneebolster brackets comprise a plurality of sections.
 18. An energyabsorbing knee bolster assembly as set forth in claim 17 wherein each ofsaid sections have at least one collapse initiator therein.
 19. Anenergy absorbing knee bolster assembly as set forth in claim 18 whereinsaid at least one collapse initiator comprises a projection and recesson adjacent said sections, said projection being received in saidrecess.
 20. An instrument panel assembly for a vehicle comprising: aninstrument panel; a knee bolster assembly attached to said instrumentpanel; and said knee bolster assembly comprising a knee deflector forpartially surrounding a steering column of the vehicle and left andright energy absorbing knee bolster brackets on opposite sides of saidknee deflector, wherein said knee deflector and said energy absorbingknee bolster brackets are integral, unitary, and one-piece.